The present invention relates generally to monitoring and protection systems for use in applications such as industrial machine control. More particularly, the invention relates to a modular system that employs rapid protection schemes via local control loops.
In industrial applications employing complex machine systems, various monitoring and protection functions are carried out. Monitoring of system parameters, for example, is performed for system evaluation, performance, control, and similar functions. In machine systems employing moving machinery, such as rotary machinery, a wide range of parameters may be monitored in this manner, such as speed, vibration, temperature, position, and so forth. Based upon the nature of the application and the desired range of such parameters, various analysis functions may be performed on sensed parameter signals to evaluate the system performance and to control the system.
In a typical monitoring and protection system in an industrial setting sensors or transducers are placed on or near desired locations on the machine and used to generate signals representative of parameters of interest. Signals from these sensors are communicated to monitoring equipment which may process the signals in accordance with pre-established algorithms. Where diverse and separate monitors or monitoring stations are employed, signals or data based upon the signals may be transmitted to remote locations where control or protection algorithms process the data to determine whether corrective action needs to be taken. Such corrective action may include notifying an operator of a particular condition, but may also extend to starting certain equipment, stopping certain equipment, sounding alarms, and so forth.
In particularly demanding applications, current standards provide for extremely rapid response to detected dynamic conditions outside the norm. By way of example, certain industrial applications require that switching of equipment power, such as to de-energize motors, valves, or other equipment, must occur within an extremely short delay following the onset of certain conditions. The conditions may include certain speeds, temperatures, and may particularly include vibration in certain mechanical systems, particularly in rotary equipment. Where abnormal levels of vibration begin to occur, delay in corrective or protective action may result in significant damage to the equipment leading to unnecessary cost and down time.
A range of systems have been developed to respond to this type of demanding application. Certain monitoring systems are currently available, for example, that provide linking of certain system components via backplanes, typically within an enclosure. Modules such as monitoring modules and relay modules may be linked to one another via the backplane to exchange data and to provide the necessary protection functions. However, such systems suffer from drawbacks in their inherent lack of true modularity due to the use of the backplane. Consequently, the modules may be placed at a distance further from the application than would be desirable, or may not be optimized due to the need for a standard backplane in situations where few monitors are used and the backplane is intended to accommodate a greater number. Moreover, communications between components on the backplane is typically via a proprietary protocol, and translation of data may be required for communication with remote equipment and monitoring stations. Such translation may complicate algorithms used to integrate both local control loops and larger control loops that tie in algorithms from the remote equipment.
There is a need, therefore, for an improved technique for providing protection in industrial machine settings. There is a particular need for an arrangement which will facilitate very rapid local protection loops and which would easily integrate modules both local to the protected equipment and modules or a central monitoring station remote from the equipment.
The present invention provides a novel monitoring and protection system designed to respond to such needs. The system is particularly well-suited for use in industrial settings where very rapid localized protection may be required for specific equipment, while less demanding monitoring or protection functions are performed in parallel. The system design may be incorporated in modules or units which are separate from one another and provide such local protection at various points in an overall machine system.
In accordance with certain aspects of the present technique, the system includes a sensor that is disposed at a location with respect to a machine to sense a dynamic operating parameter of the machine during operation. A central monitoring station is disposed remote from the sensor location. A monitoring and protection station is disposed approximate the sensor, such as near the location of interest where the sensor is placed. The station includes a monitoring module that receives and processes signals from the sensor. The station also includes a relay which is coupled to the monitoring module and is controlled by the monitoring module to apply or interrupt power to a component of the machine system. A control loop is thus established local to the machine component by which the monitoring module may rapidly respond to detected conditions. The control loop may be completely independent from the central monitoring station such that the relay is controlled very quickly and not based upon input from the central monitoring station. Reporting, however, is carried out with the central monitoring station via an open industrial data exchange protocol.
The system may be implemented such that more than one control loop is formed. A local control loop may permit very rapid changes in a switching device, such as a relay. A larger control loop, which may include other monitors, remote equipment, or a central monitoring station, employs input or logic stored at such remote locations, and may be appropriate for less time-sensitive control or protection. Where multiple monitors are provided at a single location, these preferably communicate with one another via the same open industrial data exchange protocol used to communicate with a central monitoring station. The system is thus highly modular and does not rely upon a backplane configuration for implementation of a local control loop, communication between modules at separate locations, or communication between such modules and remote devices such as central monitoring stations or computers.